DOD Overdrive 250 - Impedence weirdness?

[elgorgon]

Haven't been around here much since the forum moved, luddite tendencies of mine and all.
My modded Dod 250 was all that and then some for what I want in a distortion/overdrive pedal. Basic mods are tweaking the freq/gain cap/resistor combo to 1.5k/.27uf, increasing the input cap to .1uf and tweaking the diodes to taste. This unit has worked wonderfully in every application to the point where I scored a 2nd off ebay for backup.
The day after getting the 2nd unit the original unit no longer works directly into either my Tone King Comet or JTM45. What I get is a drastic volume loss regardless of the pedal's settings. There was a power surge around the same time at the rehearsal space so I tried swapping the opamp - the volume loss remains.
If I add a buffer after the box everything works fine. If I run the pedal through my Magnatone Varsity (similar to a Champ) or Vibro Champ at home I don't get the volume loss. Running the unmodded new unit direct to either amp also caused the volume loss.
I've mostly used this box with some type of buffer (usually a near stock Memory Man) afterwards, but I've definitely used it straight into the amp on a few gigs and jams where the volume loss didn't occur with these same amps.
Any ideas?